Building the World's Biggest Ship: Behind-the-Scenes First Look

How do you construct the most massive boat ever? One piece at a time. With the world's next generation of mega cruise liners taking shape in a Finnish shipyard, PM sends one of the world's top photographers to watch metalworkers muscle it together, part by colossal part.

On the forested coast of southern Finland, in the town of Turku, a brass band plays to a festive crowd gathered along the lip of a 1200-ft.-long, 50-ft.-deep hole. An antique cannon fires, its boom echoing off the colossal white cruise ship that looms up out of the dry dock. After a brief speech, a trio of dignitaries turns a valve. A stream of water gushes onto the floor of the pit far below. For the shipbuilders at Aker Yards, this "float-out" is a proud moment. Some 230 ft. longer than the Titanic, the 1112-ft. Independence of the Seas is an awesome behemoth, the third in a triplet of vessels that are the largest cruise ships in the world. For its owner, Royal Caribbean, the ship is an $800 million tour de force. But the Independence isn't the most remarkable thing on display in the sprawling shipyard.

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Even as the vessel is buoyed for the first time, its triumph is dwarfed by the pieces of an even larger leviathan, a $1.2 billion monster named Oasis of the Seas. The 1180-ft. Oasis represents the latest effort in an intense, decades-long race with other cruise lines to push the envelope in terms of how massively ships can be conceived and constructed. So far,the Oasis's only rival will be its own sister ship, scheduled to launch a mere 11 months afterward. But the superlatives these ships have earned may not last long.

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"The larger we build, the larger we're able to build," says Harri Kulovaara, executive vice president in charge of maritime construction at Royal Caribbean.

Inside a cavernous factory space at Aker Yards, the din of construction is deafening. Underneath a latticework of girders, the yellow glare of sodium light falls on acres of massive, reddish-brown, angular shapes. This raw material--steel sheets 39 ft. long and up to an inch thick--is being welded together to form the basic building blocks of the Oasis. With its robotic transporters and welding stations, the facility is extremely high-tech. Yet many of the techniques used here would be familiar to the ironworkers who laid down the Lusitania in 1904. Aker vice president Tom Degerman oversees the project, and as he strides across the shop floor, a clanging sound booms from inside a rust-colored section of half-completed hull. "He's adjusting the bulkhead," Degerman explains. Translation: A worker is whaling on a hunk of steel with a sledgehammer.

Constructing a ship on this scale requires a combination of brute force and advanced engineering. For hundreds of years, large vessels were built from the bottom up, with shipbuilders striking the keel and erecting the hull before adding each deck, one level at a time. Today's big builds are more efficient, but also more complicated. Components are fabricated and assembled separately, then joined one to another like so many giant Lego blocks.

The process begins at the shipyard's railhead, where steel arrives directly from the foundry. Welding machines autonomously combine the metal sheets into larger slabs that slide through a series of workstations on an 80-ft.-wide conveyor belt. Braces and other structural components are welded onto the slabs until the resulting block weighs as much as 66 tons. When it's ready, the block is hoisted and welded into a stack with three other blocks to make a "grand block" that can be the size of an 8000-sq.-ft. apartment building, complete with cables, ducts and wiring. Most of these grand blocks are assembled in Turku, with the rest put together in Germany and Lithuania.

Next, each grand block is placed atop a 36-ft.-wide, 144-wheel crawler that, trundling along at a top speed of 6 mph, carries it into the painting shop. There it is blasted from all angles with a corrosion-resistant coating. Each of the ship's 181 grand blocks are then hoisted into the dry dock and welded together, and their respective tubing, bulkheads and decks are connected. Prefabricated cabins, complete with trim, are lifted through the side of the ship and rolled on wheels into place. Thanks to this modular assembly, the building process takes only 19 months from keel-laying to launch.

The secret to building giant ships isn't larger machinery. "What's made this possible is computers," Kulovaara says. Twenty years ago plans were still drawn out by hand. Today, advanced software allows a ship's designers to imagine more complex shapes and create longer, more rigid structures. Builders can now assess how each piece of the ship will respond to loads and how they'll transmit noise and vibrations, an unwelcome problem on cruise ships.

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Moreover, three-dimensional renderings allow designers to assess not just how the ship will work, but how it will feel­--what it will be like to stroll down the central promenade or how the glittering grand dining hall will look as guests descend the spiral staircase. Given the ship's ultrafast turnaround, this sort of previsualization is crucial; there is no time to second-guess the layout during construction.

Such simulations can also help maximize safety. If a ship should run aground or start to sink, thousands of people would need to channel through its corridors in order to reach lifeboats. Swarms of virtual passengers can reveal where bottlenecks and blockages will occur. Other programs model how fire would spread through a ship, helping engineers design ways to mitigate the danger of catastrophe.

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Ships the size of the Oasis are not only challenging to build, but difficult to move through water. In a conventional vessel, engines turn driveshafts that protrude through the hull to turn the propellers. Rudders at the stern provide turning power but can only generate sideways force when the ship is moving.

There's no way a huge vessel like the Oasis could maneuver in crowded harbors with such a steering system. Instead, its propellers are driven by electric motors contained within sealed pods that hang beneath the ship. The central prop and two on either side are mounted on rotating "azipods" so that their thrust can be vectored in any direction. Four ducted propellers in the bow provide additional lateral thrust. The sophisticated steering system is integrated with automated satellite navigation, so that with the flick of a joystick the captain can maneuver the ship in any direction­ within 15 in. of accuracy. The ship can even be held in place while facing a 40-knot (46-mph) gale.

At the time of her float-out in late 2007, the Independence provided a good template for understanding the final stages of the construction of the Oasis. The liner's grand blocks have all been welded together, and from the outside it looks almost complete. Inside, however, the floor is an unadorned steel deck plate, windows are taped over with foil and exposed cable hangs from open ducts. Two thousand workers will continue to swarm over the ship six days a week until she's ready for delivery.

When a new car design rolls off the assembly line, the manufacturer can use the same tools and people to churn out a multitude of identical vehicles. Not so with cruise ships. "We spend a lot of passion and a lot of money making every detail of a new design, then after two or three ships we throw the plans away," says Hernan Zini, yard captain of the Independence. "We need to surprise the customer and come up with something new."

Historically, cruise lines used destinations as their main selling points. ("Welcome to sunny Puerto Vallarta!") But after Royal Caribbean built the first 120,000-ton cruise ship in the late 1990s, the company could pack in so many amenities that the ship itself became the draw. "Thanks to today's construction technologies, it is possible to not only carry thousands of passengers, but provide them with full-scale theaters, basketball courts and ice-skating rinks," says Terry Dale, CEO and president of Cruise Lines International Association.

Back dockside in Turku, seawater gushes with fire-hose force into the bottom of the cavernous dry dock, which will take all night to fill. Once the rising water lifts the Independence to sea level, it will float free, the dry dock will be resealed and the water pumped out again. Then, it will be Oasis's turn. The next generation of behemoth will take shape on the dry-dock floor--and this November, the cannons of Turku will boom once more.